The disclosure relates generally to additive manufacturing, and more particularly, to methods and systems for metal powder additive manufacturing a portion of an object using different melting beam sources in an overlapping field region of the sources and including overlapping border and internal sections of the portion.
Additive manufacturing (AM) includes a wide variety of processes of producing an object through the successive layering of material rather than the removal of material. As such, additive manufacturing can create complex geometries without the use of any sort of tools, molds or fixtures, and with little or no waste material. Instead of machining components from solid billets of material, much of which is cut away and discarded, the only material used in additive manufacturing is what is required to shape the object.
Additive manufacturing techniques typically include taking a three-dimensional computer aided design (CAD) file of the object to be formed, electronically slicing the object into layers, and creating a file with a two-dimensional image of each layer. The file may then be loaded into a preparation software system that interprets the file such that the object can be built by different types of additive manufacturing systems. In 3D printing, rapid prototyping (RP), and direct digital manufacturing (DDM) forms of additive manufacturing, material layers are selectively dispensed to create the object.
In metal powder additive manufacturing techniques, such as selective laser melting (SLM) and direct metal laser melting (DMLM), metal powder layers are sequentially melted together to form the object. More specifically, fine metal powder layers are sequentially melted after being uniformly distributed using an applicator on a metal powder bed. The metal powder bed can be moved in a vertical axis. The process takes place in a processing chamber having a precisely controlled atmosphere of inert gas, e.g., argon or nitrogen. Once each layer is created, each two dimensional slice of the object geometry can be fused by selectively melting the metal powder. The melting may be performed by, for example, a high powered melting beam, such as a 100 Watt ytterbium laser, to fully weld (melt) the metal powder to form a solid metal. The melting beam moves in the X-Y direction using scanning mirrors, and has an intensity sufficient to fully weld (melt) the metal powder to form a solid metal. The metal powder bed is lowered for each subsequent two dimensional layer, and the process repeats until the object is completely formed.
In order to create more objects faster or create larger objects, some metal additive manufacturing systems employ numerous high powered melting beam sources, e.g., four lasers, that work together to form numerous objects or a larger object. For speed, some of these systems employ techniques that form a shell of an object with one melting beam source using a small beam size, and a core of the object with another melting beam source using a larger beam size that melts material adjacent to the shell. Further, for speed or source balancing reasons, some of these systems employ techniques that form a portion of an object with one melting beam source, and at least a second portion with a second melting beam source that melts material adjacent thereto. In either event, the melting beams sources must be precisely aligned to ensure defects do not occur where the two melting beam sources work in adjacent areas.